Beam contacts have been widely used in applications involving circuit board edge connectors and pin connectors. In edge connector applications, many of the available structures have involved the technique of preloading the beams for the purpose of reducing circuit board insertion forces. For example, U.S. Pat. No. 3,464,054 to Mansfield discloses a connector block having contact members pretensioned against a wall for reducing the force of inserting an insulative substrate into an elongated channel. In another example, U.S. Pat. No. 3,671,917 to Ammon discloses a connector housing in which flanges on each of the terminals are held apart by an overhanging lip portion so as to preload the terminals for receiving a male pin contact.
The use of dual beams at one end of a terminal is disclosed in U.S. Pat. No. 3,665,375 to Thoms, et al. Such terminals, as shown in FIGS. 1 and 2 therein, have been used with edge board connectors.
In recent years there has been an increase in the sizes of pin fields in microcircuit applications. This has given rise to a demand for reduced insertion forces in pin connector technology. One usage involves integrally molded elongated plastic ledges in the side walls of the connector housing which preload dual beam terminals by spreading the beams apart when the terminals are inserted into housing cavities. A prime disadvantage of this system, however, is that the beams are easily damaged by the plastic ledges upon insertion into the cavities. In addition, the system does not adequately allow for non-standard pin position. Thus, a poor contact is sometimes obtained when, because the terminal is immobilized by the plastic ledges, the terminal cannot accommodate an off-set or misaligned pin.